Pulse analyzer



July 10, 1951 w. E. GLENN, JR

PULSE ANALYZER Filed Jan. 14, 1949 E El E m m e s EEE Hmmm@ l @mmm .o EEE-m EEE-m EEE EEE-m EEE Mmmm .o DEEE@ MEME@ SEEE @mE- EEE @mmm- .o mmm El E! E TTORNEY Patented July 10, 1951 I PULSE ANALYZYEB William,E.rGlen n, Jr., Birmingham, Ala., assignv or to the United States of America as repre@- sented by the United- States` Commission Atomic IEnergy Application January 14, i949, serial No. 70,865

Claims. (Cl. 2354-92) This invention relates to a method and apparatus for analyzing pulses of voltage and more particularly to an apparatus rfor sorting and counting pulses of voltage at predetermined amplitudes. Y

Pulse analyzers have been developed employing intricate circuits employing a plurality vof biased discharge tubes. `The inherent characteristics of such discharge tubes introduce errors because of drift which necessitates recalibration each time the analyzer is used. Other disadvantages with such pulse analyzers are their inability to count pulses having a short dura-` tion and their sluggishness of operation. The present invention uses an electron gun arrangement similar to that of a cathode ray tube for producing an electron beam, theA deflection of which is controlled by the input voltage pulses. The pulse height selectingA circuit is simple and free from errors due to tube characteristics and provides a simple and rapid method oi determining the number of voltage pulses occurring between two predetermined amplitudes.

It is therefore an object of the, present invention to provide a new and improved pulse analyzer.

y A primary object of the present invention is to provide a pulse analyzer which is capable of handling pulses of very short duration and which operates in an extremely fast manner.

YAnother object of the present invention is to provide a pulse analyzer characterized by its simplicity and accuracy.

A further object of the present invention is to provide a pulse analyzer which counts pulses of voltage having the same amplitude over a large range or' amplitudes.

A still furtherv object vof the present invention is to provide a new and improved method of sorting and counting pulses of voltage having the same amplitude for a large variation of peak voltages. i

Another object of the invention is to provide a pulsev analyzer employing a modied cathode ray type tube for counting pulses of the same amplitude. Y

Other objects and advantages will be apparent in the following description considered together with the accompanying drawing in which the present invention is shown in 'schematic form.

shown a substantially conical envelope II diverging into a flanged portion I2.

l Considering the drawing in detail, there is' um seal 38 in the envelope II.

In order to make an airtight seal between the cover plate I3 and the flange I2, a washer I6 of rubber or similar material is provided therebetween. A plurality of targets I'I is mounted centrally in a linear spaced-apart and staggered array along the length of the cover plate I3 and each of the targets I'I has an electricallyconducting lead I8 brought out through a vacuum sealtype connector (not shown) in the cover plate I3. An electron gun arrangement is disposed axially at the other end of the envelope II and comprises a heater filament I9, a cathode 2|, a control grid 22, a focusing electrode23, an accelerating electrode 24, a pair ,of deflecting plates 26 and 2l, and a pair of vertical deflecting plates (not shown).

A source of electrical pulses 28, such as an ionization chamber, is connected by two wires 29 and 3l to a pulse amplifier 32. The output voltage of the pulse amplier is connected by two leads 33 and 34 to a discriminator 3B and by a wire 31 to the deflecting plate 2t through a vacu- The output voltage of the discriminator 36 is connected between the cathode 2 I, by a lead 4I, and the controlV grid ments of the electron gun a power supply 45 is i provided. A heater voltage is connected from av pair of terminals 41 and 48 of the'power supply 46 by two leads49 and 50 to the filament I9 through vacuum seals 5I and 52 respectively inl the envelope II. Another terminal 53 supplies a common connection for the other voltages of the power supply 46 and is connected by a lead 54 to the` cathode 2|. An accelerating voltage is connected from a terminal 56 of the power supply 46 by a wire 51 through a vacuum seal 58 in the envelope II to the focusing electrode 23. The powerY supply 46 furnishes an accelerating voltage to the accelerating electrode 24 by a lead BI connected betweenthe accelerating electrode 24 and a terminal 62 on the power supply 4S through a vacuum seal 163 in the envelope I I. A further voltage is connected from a terminal 66 of the power supply 46 by a wire 61 through a vacuum seal 68 inthe envelope II to the deecting plate 21. vlor vertically centering the electron beam the vertical deflecting plates (not shown) may be connected in a conventional cathode ray tube. manner to a suitable source of Yunidirectional power.

The leads I8 connected to the plurality of targets I1 are each connected to individual amplifiers 1I, the output voltages of which are connected to a like number of mechanical registers 12 by leads 13.

Prior to operation of the present invention, it is necessary to 'assemble the electron gun elements within lfthe envelope I'I, "bolt the 'cover plate I3 carrying the targets I1 to the flange I2 with the rubber washer I6 as an airtight seal therebetween, and evacuate the resultingchamber formed. Then with the connections between the electron gun elements andlthe power-iSupply 46 made, as previously described, the -power 'supply 46 is energized. Under these conditionsthe filament I9 becomes heated, thereby rendering the cathode 2I electron-emissive. iSincev'the control grid 22 has no potential applied, the focusing electrode 23 is positive with respect `Yto the cathode 2|, and the accelerating electrode 24 is positive :withirespect/to the focusing-electrode 23, the :electrons emittedat the cathode "2| :are attractedaway from the region of thec'athode -2I, focused byfthe focusing electrode'ZS, andaccelerated by Ithe accelerating 'el'ectrode 24. v'The elec-- trons :thus accelerated through ithe ypositive electric 4held-of the accelerating electrode :then pass through the :electric `ield of the deflecting plate 21. The potential applied to -the vdeflecting plate 21 is 'negative tocurvefthe electrons "away from the plate -2-1 and should be adjusted vso thatthe electron beam impinges at a vpoint X adjacent the end target I1 which is ithe furthest 4from :the deilecting plate 2-1 The nextstep is to connect the 'targets I1, :as described hereinbefore, to the mechanical registers `r12 through the ampliers 1I. Under this condition, it is a simple matter to ydetermine the values of voltage necessary to cause -a'deflection of thefelectron beamso-that each lcounter will be operated 3by connecting a variable power supply (not shown) tothe deecting plate26'and noting the voltage at which each register I2 operates. These valuesof voltages may 'beca'lculated with a fair degree of accuracy, since lthe accelerating voltage and tubeldimensi'ons are known; however, calibration ywith a variable power supply .is preferable.

Now, with the foregoing `adjustment and calibration-accomplished, the remaining 'connections as described in the foregoing paragraphs, should be made. The discriminator '36 `is `so constructed that A'the control grid '22 of the electron gun is normally 'biased with afsuiciently large value of negative `voltage *to prevent electronspassing fromthe region of the cathode 2i into thepositive electric fields of lthe focusing electrode l23 and the `accelerating .electrode v424.

The Ioccurrence of Aa vpulse of voltage at 'the output of 'the amplier`32, .inresponsete aninput pulse of 'voltage of unknown magnitude from an electrical device, such as 'the ionization chamber 28, causes such a voltage to befapplied to .the discriminator 36 and to therdeflect'ing -plate .'26 of the electron gun. The discriminator .(3'6, inaddi tion to being constructed to apply the normal cut-olf bias to 'the control .grid 22.,lis also .con-- 2I` are momentarily allowed to pass through the` control grid 2v2 and into the electric fields of the focusing electrode '23 and the ,accelerating electrode '24. Since the 'output pulse of voltage lof the pulse amplifier is negative and i'sinpressed on the deecting plate 26, the electric elds of the two delecting plates 26 and 21 are in opposition and the deflection of the electron beam by the deflecting plate 21 will be altered in accordance with the peak value of the voltage pulse at the deflecting plate 26. Thus it Will be seen that the electron beam will be -deiected to LLimpinge on the xtarget I1 icorresponding to the rvrvalue of the peak voltage. The electron beam current at the target I1 is then amplified through the corresponding amplier 1I to operate the corresponding register 12.

vFrom the foregoing, it is apparent that each pulseof voltage will be accurately and propor- "tionately recorded'on a register 12 such that each count of that register 12 represents a pulse of voltage'of a certainheight The proportionality mentioned arises from the use of the amplifier 32 in 'the signal input circuit.

Numerous uses of the present invention are obvious and one such use 'has been presented herein fby showing the ionization chamber 28a's the source of voltage pulses. Byusingthe ionization chamber 28, itis possible todetermine 'the energy levels of the particles of radiation to which the chamber has lbeen exposed.

'While -the salient features of the present invention have -been Vdescribed in 'detail with respect to one embodiment, itwill, vof course, be

apparent that numerous modifications may be' 'tive Yto project an electron beam therefrom,

means for deiiecting said electron beam "in vaccordance with'said pulse, and means for l'deter-V mining the degree of deflection as a function of..

the Y'peak valueof saidLpulse l 2. Apulse analyzer for sorting 'and icounting pulses of 'voltage 'comprising an'evacuated 4enf velope, an electron gun disposed at one en'd fof said envelope, a plurality'ofsimilartar'getmeans mounted centrally at the other end of vsaid envelope ina pair of linearly spaced-apart 'and alternately staggered rows Vand disposed trans-v versely of the axis of said electron gun "to provide acontinuous series of separate target'm'ea'n's.,

means for energizing 'said electron gun whereby an electron beam is generated, `means for 'normally biasingsaid electrongun 'a't 'cut-'oifjinean's responsive only to the peak value of a pulse 3t`o be analyzed vfor 'removing 'said normal 'bias at such value, means for Sde'ecting 'said electron beam in accordance with said pulse, and means connected to said targets for indicating the particular Vvtarget which intercepts said deflected beam.

3. A Fpulse 'analyzer for 'sorting and counting. pulses of voltage comprising a substantially conical evacuated envelope, an electron .gun having a cathode, 4control grid, focusing 'electrodeV accelerating electrode, and deiiecting :plates disposed aXiallyinspaced-apart relation at ytheconverging 'end Vof said envelope, a plurality of similar targets centrally mounted at the other end of said envelope, said targets being disposed in two linear rows spaced apart along the aXis of said electron gun and transverse thereto, the targets of each row being spaced apart substantially the width of one of said targets with the targets ol' one row alternately staggered with respect to the other to provide a continuous series of separate targets, means connected to said electron gun for supplying operating voltages thereto, means for normally maintaining said control grid negative to prevent a iiow of electrons through said electron gun, means for supplying a pulse to be analyzed to one of said deflecting plates and at the peak value thereof to said control grid whereby the negative bias on said control grid is removed and the resulting electron ybeam deected, and means for indicating which of said targets intercepts said electron beam as a function of the peak voltage of said pulse.

4. A pulse analyzer for sorting and counting pulses of voltage comprising a substantially conical evacuated envelope, an electron gun having a cathode, control grid, focusing electrode, accelerating electrode, and deflecting plates disposed axially in spaced-apart relation at the converging end of said envelope, a plurality of similar targetsY centrally mounted at the other end of said envelope, said targets being disposed in two linear rows spaced apart along the axis of said electron gun and transverse thereto, the targets of each row being spaced apart substantially the width of one of said targets with the targets of one row alternately staggered with respect to the other to provide a continuous series of separate targets, electrical means for supplying operating voltages to said electron gun, a source of pulses to be analyzed, means for amplifying said pulses, means for normally biasing said control grid sufficiently negative to prevent an electron beam being formed by said electron gun, said biasing means also being connected to the output of said amplifier and including means responsive to the peak value of said amplified pulse to remove said normal bias, means connecting the output of said amplifier to one of said delecting plates to deect the electron beam to one of said targets, and means for indicating the particular target which intercepts said deiiected beam.

5. A pulse analyzer for sorting and counting pulses of voltage comprising a substantially conical evacuated envelope, an electron gun having a cathode, a control grid, focusing electrode, accelerating electrode, and deflecting plates disposed axially in spaced-apart relation at the converging end of said envelope, a plurality of similar targets centrally mounted at the other end of said envelope, said targets being disposed in two linear rows spaced apart along the axis of said electron gun and transverse thereto, the targets of each row being spaced apart substantially the width of one of said targets with the targets of one row alternately staggered with respect to the other to provide a continuous series of separate targets, electrical means for supplying operating voltages to said electron gun, a source of pulses to be analyzed, means for amplifying said pulses, means for normally biasing said control grid suiciently negative to prevent an electron beam being formed by said electron gun, said biasing means also being connected to the output of said amplier and including means responsive to the peak value of said ampliiied pulse to remove said normal bias, means connecting the output of said amplifier to one of said deflecting plates to deflect the electron beam to one of said targets, an ampliiier connected to each of said targets, and an electromechanical register connected to each of said amplifiers for recording the number of pulses as a function of peak voltage.

WILLIAM E. GLENN, J R.

REFERENCES CITED The following referencesl are of record in the file of this patent:

UNiTED STATES PATENTS Number Name Date 1,946,223 Mason Feb. 6, 1934 2,053,268 Davis Sept. 8, 1936 2,224,677 Hansom Dec. 10, 1940' 2,257,795 Gray Oct. 7, 1941 2,267,827 Hubbard Dec. 30, 1941 2,287,296 Dallos June 23, 1942 2,301,748 Renshaw Nov. 16, 1942 2,361,766 Hadekel Oct. 31, 1944 2,462,896 Ransom Mar. l, 1949 2,477,008 Rosen July 26, 1940 2,480,130 Grieg Aug. 30, 1949 2,496,633 Llewellyn Feb. 7, 1950 

